Search Results (93)

The Sonora Estuarine Biocultural Corridor (CBES) is made up of six coastal wetlands with mangrove forest, internationally certified as Ramsar Sites. Four are part of indigenous territories whose inhabitants have serious development lags and low water security. Five are within one or more of six irrigation districts of national relevance. The objective is to learn about the socio-environmental problems of the CBES, focused on the issue of water, as well as community proposals for solutions. Intercultural, mixed methodology approach. Prospecting visits were carried out in the six estuaries of the CBES, and 84 semi-structured interviews were conducted with experts from all social sectors who know the problems of the CBES in three (out of six) estuaries associated with indigenous territories. The main problem is centered on the issue of water: they receive contaminated water from agroindustry, aquaculture, and the municipal service; the fresh water of the rivers is almost nil, rainfall has decreased while the heat increases, and marine and terrestrial biodiversity decreases. This affects the food and economic security of the local population and generates conflicts between the different productive activities. A multisectoral organization that integrates the six estuaries would improve community wellbeing and, in turn, climate resilience. Full article

Coastal wetlands are critical ecosystems that require effective monitoring to support conservation and restoration efforts. This study evaluates the use of small unmanned aerial systems (sUAS) and multispectral imagery to estimate aboveground biomass (AGB) in tidal marshes, comparing models calibrated with destructive versus non-destructive in situ sampling methods. Imagery was collected over South Carolina’s North Inlet-Winyah Bay National Estuarine Research Reserve, and vegetation indices (VIs) were derived from sUAS imagery to model biomass. Stepwise linear regression was used to develop and validate models based on both sampling approaches. Destructive sampling models, particularly those using the Normalized Difference Vegetation Index (NDVI) and Difference Vegetation Index (DVI), achieved the lowest root mean square error (RMSE) values (as low as 70.91 g/m²), indicating higher predictive accuracy. Non-destructive models, while less accurate (minimum RMSE of 214.86 g/m²), demonstrated higher R² values (0.44 and 0.61), suggesting the potential for broader application with further refinement. These findings highlight the trade-offs between ecological impact and model performance, and support the viability of non-destructive methods for biomass estimation in sensitive wetland environments. Future work should explore machine learning approaches and improved temporal alignment of data collection to enhance model robustness. Full article

Suaeda salsa, a halophytic plant species, exhibits a remarkable salt tolerance and demonstrates a significant phytoremediation potential through its capacity to absorb and accumulate saline ions and heavy metals from soil substrates, thereby contributing to soil quality amelioration. Furthermore, this species serves as a critical habitat component for avifauna populations and represents a keystone species in maintaining ecological stability within estuarine and coastal wetland ecosystems. With the development and maturity of UAV remote sensing technology in recent years, the advantages of using UAV imagery to extract weak targets are becoming more and more obvious. In this paper, for Suaeda salsa, which is a weak target with a sparse distribution and inconspicuous features, relying on the high-resolution and spatial information-rich features of UAV imagery, we establish an adaptive contextual information extraction deep learning semantic segment model (ACI-Unet), which can solve the problem of recognizing Suaeda salsa from high-precision UAV imagery. The precise extraction of Suaeda salsa was completed in the coastal wetland area of Dongying City, Shandong Province, China. This paper achieves the following research results: (1) An Adaptive Context Information Extraction module based on large kernel convolution and an attention mechanism is designed; this module functions as a multi-scale feature extractor without altering the spatial resolution, enabling a seamless integration into diverse network architectures to enhance the context-aware feature representation. (2) The proposed ACI-Unet (Adaptive Context Information U-Net) model achieves a high-precision identification of Suaeda salsa in UAV imagery, demonstrating a robust performance across heterogeneous morphologies, densities, and scales of Suaeda salsa populations. Evaluation metrics including the accuracy, recall, F1 score, and mIou all exceed 90%. (3) Comparative experiments with state-of-the-art semantic segmentation models reveal that our framework significantly improves the extraction accuracy, particularly for low-contrast and diminutive Suaeda salsa targets. The model accurately delineates fine-grained spatial distribution patterns of Suaeda salsa, outperforming existing approaches in capturing ecologically critical structural details. Full article

The intertidal zones of estuarine wetlands serve as critical components in maintaining and promoting the sustainable development of regional ecosystems. Salt marsh vegetation, a crucial element of these zones, is experiencing significant deterioration across multiple scales due to various stressors. Despite considerable attention given to the spatial patterns and temporal evolution of salt marsh vegetation, few studies have quantitatively assessed its dynamic interactions with tidal creeks. Tidal creeks serve as primary conduits for material, energy, and information exchange between intertidal zones and adjacent ecosystems. There is a complex feedback mechanism between the development of the tidal creeks and vegetation communities. We investigated the distribution patterns and successional characteristics of salt marsh vegetation at both landscape and pixel scales, with particular emphasis on coupling dynamics with tidal creeks. Our results revealed a distinct spatial gradient in vegetation distribution across the study area. While the invasion of S. alterniflora exhibited limited direct competitive effects on S. salsa, it demonstrated significant influence on tidal creek geomorphological evolution. Notably, S. salsa exhibited pronounced sensitivity to hydrological conditions, with its growth being substantially constrained by tidal creek development and associated soil modifications. Full article

Multi-driver interactions shape estuarine wetland evolution, yet the intricate evolution patterns and their controlling factors their spatiotemporal dynamics remain inadequately understood. This study employs high-resolution satellite data (1985–2020) and 3S technology (overall classification accuracy: 92.44%, Kappa coefficient: 0.9132) to reveal the development of tidal creeks and vegetation evolution patterns of the Dongtan wetland. Our findings indicate a transition in the development of tidal creeks and vegetation from a natural stage to an artificial intervention stage. Northern regions exhibited severe degradation of both vegetation and tidal creeks influenced by reclamation, contrasting with southern recovery post-restoration. This disparity highlights the varied responses to human activities across different areas of the Dongtan wetland. Notably, the introduction of the invasive species Spartina alterniflora has negatively impacted the habitat of native vegetation. The interaction mechanism between vegetation and tidal creeks manifest as: vegetation constrains tidal creek development through substrate stabilization, wave dissipation, and sediment retention, while tidal creeks modulate physicochemical properties of the substrate hydrological connectivity and seed dispersal, affecting vegetation zonation and community structures. Human activities exert dual modulation effects on the Dongtan wetland, driving its phase transition from natural to artificial landscapes, with artificial landscapes exhibiting the most dynamic landscape type through reclamation and ecological restoration projects. Our findings enhance the understanding of the mechanisms underlying estuarine wetland development and inform strategies for restoring healthy estuarine wetland ecosystems. Full article

Nature reserves are integral to sustaining ecological balance, functioning like a precise ecological regulator, where various species depend on and constrain one another to collectively form a stable ecosystem. Nevertheless, in the wake of economic development, pollutants like heavy metal contamination have insidiously emerged, imperceptibly influencing all these processes. To understand the ecological risk of heavy metals in an estuarine nature reserve, this study focused on the Yellow River Delta Nature Reserve (YRDNNR) and analyzed the distribution, potential environmental risks, and possible sources of heavy metals (Mn, Cu, Zn, Cr, As, Cd, Pb) in the surface sediments of this region. The results indicated that YRDNNR was rich in As and Cd, with Cd presenting the most substantial ecological risk. Further analysis suggested that the high levels of As and Cd could be ascribed to agricultural activities. This study also found that agricultural practices have made a significant contribution to the carcinogenic risk and pose certain risks to the natural environment and human health. More in-depth monitoring and testing of As and Cd levels in YRDNNR should be carried out, and measures should be adopted in accordance with their development. Moreover, the systematic regulation of fertilizer and pesticide use, along with enhancements to farmers’ ecological awareness, is of great significance to alleviating pollution hazards. The findings of this study carry significant implications for the ecological conservation of coastal wetlands, serving as a critical alert to the potential proliferation of heavy metal contamination in other areas of the delta. Full article

Mangrove forests are intertidal ecosystems that harbor diverse microbial communities essential for biogeochemical cycles and energy flow. This study investigated the seasonal and spatial patterns of bacterial communities in the artificially introduced mangrove sediments of the Ao River estuary using 16S rRNA gene amplicon high-throughput sequencing. Alpha diversity analyses indicated that the bacterial community diversity in the mangrove sediments of the Ao River estuary was similar to those of natural-formed mangroves, with the Shannon index ranging from 5.16 to 6.54, which was significantly higher in winter compared to other seasons. The dominant bacterial phyla included Proteobacteria (43.65%), Actinobacteria (11.55%), Desulfobacterota (11.16%), and Bacteroidetes (5.52%), while beta diversity analysis revealed substantial differences in bacterial community structure across different seasons and regions. For instance, the relative abundance of Woeseiaceae and Bacteroidota during the summer was significantly higher than that observed in other seasons. And the relative abundance of Bacillaceae in autumn and winter increased by one order of magnitude compared to spring and summer. Woeseiaceae, Desulfobulbaceae, Thermoanaerobaculaceae, and Sva1033 (family of Desulfobacterota) exhibited significantly higher relative abundance in the unvegetated area, whereas Bacillaceae and S085 (family of Chloroflexi) demonstrated greater abundance in the mangrove area. Seasonal variations in bacterial community structure are primarily attributed to changes in environmental factors, including temperature and salinity. Regional differences in bacterial community structure are primarily associated with environmental stressors, such as wave action, fluctuations in salinity, and organic matter content, which are further complicated by seasonal changes. This study is significant for understanding the microbial diversity and seasonal dynamics of estuarine mangrove wetlands, and it contributes to the assessment of mangrove wetland restoration efforts in Zhejiang Province, providing important guidance for the development of strategies to maintain the health of mangrove ecosystems in the future. Full article

Qinghai Lake, the largest inland saline lake in China, plays a vital role in wetland carbon cycling. However, the structure and function of soil bacterial communities in its estuarine and nearshore estuarine wetlands remain unclear. This study examined the effects of wetland type and soil depth on bacterial diversity, community composition, and functional potential in the Shaliu, Heima, and Daotang River wetlands using high-throughput sequencing. The results showed that wetland type and soil depth significantly influenced bacterial communities. Nearshore wetlands exhibited lower bacterial diversity in the 0–10 cm layer, while deeper soils (10–20 cm) showed greater regional differentiation. Estuarine wetlands were enriched with Proteobacteria, Actinobacteriota, and Chloroflexi, whereas nearshore wetlands were dominated by Actinobacteriota and Cyanobacteria. Functionally, estuarine wetlands had higher sulfate reduction and anaerobic decomposition potential, with Desulfovibrio, Desulfobacter, and Desulfotomaculum regulating sulfur cycling and carbon decomposition. In contrast, nearshore wetlands showed greater nitrogen fixation and organic matter degradation, facilitated by Rhizobium, Azotobacter, Clostridium, and nitrogen-fixing Cyanobacteria (e.g., Anabaena, Nostoc). Microbial metabolic functions varied by depth: surface soils (0–10 cm) favored environmental adaptation and organic degradation, whereas deeper soils (10–20 cm) exhibited lipid metabolism and DNA repair strategies for low-oxygen adaptation. These findings highlight the spatial heterogeneity of bacterial communities and their role in biogeochemical cycles, providing insights into wetland carbon dynamics and informing conservation strategies. Full article

Various types of tidal barriers are used in estuaries to reduce saltwater intrusion and regulate freshwater discharge, but they often alter the physicochemical environment and faunal composition. With the use of these structures expected to increase due to climate change, there is a need to understand their impacts. A tidal exclusion barrier in the Ramsar-listed Vasse–Wonnerup Estuary (Australia) was found to act as an ecotone, fragmenting the estuarine gradient into two distinct components, a relatively stable marine-like environment downstream and a highly variable oligohaline to hypersaline (~0 to >100 ppt) environment upstream. The downstream regions contained a speciose and functionally rich estuarine fauna, comprising mainly polychaetes and bivalves. The upstream regions were taxonomically and functionally depauperate, containing insects, gastropods, and ostracods typically found in saline wetlands. The fragmentation of the estuary has likely impacted the provision of ecosystem services, with the fauna downstream mainly comprising burrowing species that bioturbate and, thus, aid in nutrient cycling. In contrast, the environmental conditions caused by the barrier and the resultant epifaunal invertebrate assemblages upstream aid little in bioturbation, but provide nutrition for avian fauna. These results may help in understanding the impacts of constructing new barriers in coastal ecosystems in response to climate change. Full article

Estuarine wetlands are the transition zone between marine, freshwater, and terrestrial ecosystems and are more ecologically fragile. In recent years, the spread of exotic vegetation, specifically Spartina alterniflora, in the Yellow River estuary wetlands has significantly encroached upon the habitats of native species such as Phragmites australis, Suaeda glauca Bunge, and Tamarix chinensis Lour. With advances in land prediction modeling, predicting wetland vegetation distribution can aid management and decision-making for ecological restoration. We selected the core area as the study object and coupled the hydrological model MIKE 21 with the PLUS model to predict the potential future distribution of invasive and dominant species in the region. (1) Based on the fine classification results from satellite images of GF1/G2/G5, we gained an understanding of the changes in wetland vegetation types in the core area of the reserve in 2018 and 2020. (2) Using public data such as ERA5 and GEO as input for basic environmental data, using MIKE 21 to provide high-spatial-resolution hydrodynamic parameters for the PLUS model as an environmental driver, we modeled the spatial distribution of various wetland vegetation in the Yellow River estuary wetland in Dongying under different artificial restoration measures. (3) We predicted the 2022 distribution of typical vegetation in the region, used the classification results of GF6 as the actual distribution, compared the spatial distribution with the actual distribution, and obtained a kappa coefficient of 0.78; the predicted values of the model are highly consistent with the true values. This study combines the fine classification results of vegetation based on hyperspectral remote sensing, the construction of a coupled model, and the prediction effect of typical species, providing a reference for constructing and optimizing the vegetation prediction model of estuarine wetlands. It also allows scientific and effective decision-making for the management of ecological restoration of delta wetlands. Full article

Estuarine constructed wetlands (ECWs) play a role as ecological barriers in the control of external pollution in lakes. Usually, ECWs show reduced water treatment efficiency after many years of operation compared to their initial performance. However, it is unclear how the water purification efficiency of an ECW changes over time. After over a decade of tracking analysis on an ECW, this study found that it indeed played a significant role in achieving water quality improvement effects. The average removal rates for total nitrogen (TN) and total phosphorus (TP) and the permanganate index (COD_Mn) were 36.2%, 26.7%, and 30.7%, respectively, with annual reductions of 1.6 t/a, 20.8 t/a, and 44.6 t/a. The surface hydraulic load is a critical indicator for the design and operational management of ECWs. The reduction loads of TP, TN, and COD_Mn increased with the rise in surface hydraulic load, indicating that this ECW project had certain advantages in treating large-volume water bodies. However, when strict COD_Mn treatment is needed, the surface hydraulic load should be reduced. During the high-efficiency period (2010–2015), the treatment effects on TN and TP were more than twice those during the degradation period (2016–2021), and the effect on COD_Mn was about 1.5 times greater. With increased operation years, the TN removal rate declined most rapidly due to pollutant accumulation and sediment release. Full article

A marine nature reserve is an area designated by law for the special protection and management of sea areas, coasts, estuarine wetlands, islands, and other sea areas needing special protection, including objects of exceptional conservation value. The purpose of these reserves is to protect the natural environment and natural resources of the sea. The construction of China’s marine protected areas can be traced back to establishing the Snake Island Nature Reserve in 1963. Over the past six decades, China has established a network of marine protected areas, including marine nature reserves and marine specially protected areas (including marine parks), which have played a pivotal role in safeguarding the marine environment and biodiversity, promoting the integration of land and sea, and defending the country’s maritime rights and interests. Nevertheless, the construction of China’s marine nature reserves is a challenge to solve. It is imperative to further advance the construction and development of China’s marine nature reserves by enhancing the spatial planning of marine nature areas, streamlining the management system, and delineating the rights and interests associated with using sea areas. Full article

Solar-induced chlorophyll fluorescence (SIF) offers significant potential as a novel approach for quantifying carbon and water cycling in coastal wetland ecosystems across multiple spatial scales. However, the mechanisms governing these biogeochemical processes remain insufficiently understood, largely due to the periodic influence of tidal inundation. In this study, we investigated the effects and underlying mechanisms of meteorological and tidal factors on the relationships between canopy-level solar-induced chlorophyll fluorescence at 760 nm (SIF₇₆₀) and key ecosystem processes, including gross primary productivity (GPP) and evapotranspiration (ET), in coastal wetlands. These processes are critical components of the ecosystem carbon and water cycles. Our approach involved a comparative analysis of simulations from the Soil Canopy Observation, Photochemistry and Energy Fluxes (SCOPE) model with field measurements. The results showed that: (1) simulations of SIF₇₆₀ improved following observation-based calibration of the fluorescence photosynthesis module in the SCOPE model; (2) under optimal moisture and temperature conditions (VPD 1.2–1.4 kPa and temperatures of 20–23 °C for air, soil, and water), the simulations of GPP, ET, and SIF₇₆₀ were most accurate, although salinity stress reduced performance. GPP simulations tended to overestimate under drought stress but improved at higher air temperatures (30–32 °C); (3) during tidal inundation, the SIF₇₆₀-GPP relationship weakened while the SIF₇₆₀-ET strengthened. The range of significant correlations between SIF₇₆₀, water levels, and temperature narrowed, with both relationships becoming more complex due to salinity stress. These findings suggest that tidal inundation can alleviate temperature stress on photosynthesis and transpiration; however, it also decreases photosynthetic efficiency and alters radiative transfer processes due to elevated salinity and water levels. These factors are critical considerations when using SIF to monitor GPP and ET dynamics in coastal wetlands. This study demonstrated that the tidal dynamics significantly affected the SIF₇₆₀-GPP and SIF₇₆₀-ET relationships, underscoring the necessity of incorporating tidal influences in the application of SIF remote sensing for monitoring GPP and ET dynamics. The results of this study not only contribute to a deeper understanding of the mechanisms linking SIF₇₆₀ with GPP and ET but also provide new insights into the development and refinement of SIF-based remote sensing for carbon quantification in coastal blue-carbon ecosystems on a large-scale domain. Full article

Soil bacterial communities play a crucial role in the functioning of estuarine wetlands. Investigating the structure and function of these communities across various wetland types, along with the key factors influencing them, is essential for understanding the relationship between bacteria and wetland ecosystems. The Liaohe Estuary Wetland formed this study’s research area, and soil samples from four distinct wetland types were utilized: suaeda wetlands, reed wetlands, pond returning wetlands, and tidal flat wetlands. The structure and function of the soil bacterial communities were examined using Illumina MiSeq high-throughput sequencing technology in conjunction with the PICRUSt analysis method. The results indicate that different wetland types significantly affect the physical and chemical properties of soil, as well as the structure and function of bacterial communities. The abundance and diversity of soil bacterial communities were highest in the suaeda wetland and lowest in the tidal flat wetland. The dominant bacterial phyla identified were Proteobacteria and Bacteroidota. Furthermore, the dominant bacterial genera identified included RSA9, SZUA_442, and SP4260. The primary functional pathways associated with the bacterial communities involved the biosynthesis of valine, leucine, and isoleucine, as well as lipoic acid metabolism, which are crucial for the carbon and nitrogen cycles. This study enhances our understanding of the mutual feedback between river estuary wetland ecosystems and environmental changes, providing a theoretical foundation for the protection and management of wetlands. Full article

Tidal flats, a critical part of coastal wetlands, offer unique ecosystem services and functions. However, in China, these areas are under significant threat from industrialization, urbanization, aquaculture expansion, and coastline reconstruction. There is an urgent need for macroscopic, accurate and periodic tidal flat resource data to support the scientific management and development of coastal resources. At present, the lack of macroscopic, accurate and periodic high-resolution tidal flat maps in China greatly limits the spatio-temporal analysis of the dynamic changes of tidal flats in China, and is insufficient to support practical management efforts. In this study, we used the Google Earth Engine (GEE) platform to construct multi-source intensive time series remote sensing image collection from Sentinel-2 (MSI), Landsat 8 (OLI) and Landsat 9 (OLI-2) images, and then automated the execution of improved MSIC-OA (Maximum Spectral Index Composite and Otsu Algorithm) to process the collection, and then extracted and analyzed the tidal flat data of China in 2018 and 2023. The results are as follows: (1) the overall classification accuracy of the tidal flat in 2023 is 95.19%, with an F1 score of 0.92. In 2018, these values are 92.77% and 0.88, respectively. (2) The total tidal flat area in 2018 and 2023 is 8300.34 km² and 8151.54 km², respectively, showing a decrease of 148.80 km². (3) In 2023, estuarine and bay tidal flats account for 54.88% of the total area, with most tidal flats distribute near river inlets and bays. (4) In 2023, the total length of the coastline adjacent to the tidal flat is 10,196.17 km, of which the artificial shoreline accounts for 67.06%. The development degree of the tidal flat is 2.04, indicating that the majority of tidal flats have been developed and utilized. The results can provide a valuable data reference for the protection and scientific planning of tidal flat resources in China. Full article